Flexible touch-sensitive matrix cathode ray tube

ABSTRACT

A touch-sensitive matrix cathode ray tube for inputting and displaying data comprising a plurality of carbon nanotubes defining a plurality of pixels and a plurality of inputting elements, which consists of a dot matrix of each dot comprising a pixel and an inputting element, each pixel made up of ends of at least three mutually parallel nanotubes and each transmitting in one of the three primary colours, the input element being constituted of the end of at least a fourth nanotube.

This is application is a 371 of PCT/FR99/01029 filed Apr. 30, 1999.

The present invention relates to a touch-sensitive matrix screen andmore specifically to those constructed by using a plurality ofnanotubes.

BACKGROUND OF THE INVENTION

Traditionally, in computing, the data inputting is carried out by meansof a peripheral unit such as a keyboard or a mouse, while thevisualisation is obtained by means of a screen of the cathode tube typeor of the liquid crystal or plasma type.

Cathode screens are heavy and bulky, and emit a high radiation that isharmful for the user. The liquid crystal display or plasma screens areless bulky, but they are very fragile and do not offer a very highbrightness. Furthermore, field effect flat screens are very expensivebecause the manufacture is necessarily mainly hand-made.

Generally, the fact that the inputting device is normally separated fromthe visualisation means produces, in computing, a disjunction betweenthe hand which inputs and the sight which controls, unlike writing onpaper, where the hand and the eye operate simultaneously at the sameplace.

To avoid this drawback, touch-sensitive screens, which allow givingorders to a computer by pointing a finger or a stylus on a screen, havebeen developed. However, these systems are slow and do not allow a verygood resolution, for example when inputting a drawing or a text with thehelp of a stylus. Furthermore, certain flat screens do not tolerate thelocal pressure, even though it is minimal, of a finger or of a stylus.

SUMMARY OF THE INVENTION

The aim of the present invention is to eliminate the above mentioneddrawbacks by determining a light flexible touch-sensitive matrix screenallowing a precise inputting.

The invention uses a plurality of nanotubes,

As it is known, the nanotubes are tubes formed by carbon foils arrangedin hollow concentric cylinders and were discovered in 1991 by SumioLijima. As a reminder, a nanotube is a polymer composed only of carbonand it is a unidirectional periodic crystal.

Many articles regarding the manufacture of the nanotubes have beenpublished. One can, for example, consult the journal LA RECHERCHE num.307, of March 1998, the journal SCIENCE, Volume 282 of Nov. 6, 1998 orthe document WO-A-97/19208. One can also consult the following sites onthe Internet (having all of them the prefix http://www.) on the subjectof the manufacture and applications of the nanotubes, namelyarchipress.org, cerca.umontreal.ca/science, research.ibm.com/topics,amsci.org/amsci/articles, amsci/articles, and others.

The invention is situated in this context and allows to remedy thelimits of the traditional screens and, consequently, to contributemainly but not exclusively, to a better use of personal and professionalcomputing. The aim of the present invention is first to determine atouch-sensitive matrix screen not having the abovementioned drawbacks.Another aim of the invention is to determine such a touch-sensitivematrix screen that is not very thick and that is flexible and not veryfragile.

These aims are reached, according to the invention, with atouch-sensitive matrix screen for inputting and displaying datacomprising a plurality of carbon nanotubes defining a plurality ofpixels and a plurality of inputting elements.

According to the invention, this touch-sensitive matrix screen consistsof a dot matrix of each dot comprising a pixel and an inputting element,each pixel made up of ends of at least three mutually parallel nanotubesand each transmitting in one of the three primary colours, the inputelement being made up of the end of at least a fourth nanotube.

Advantageously, each point consists of a plurality of nanotube ends ofwhich at least four are made active.

Preferably, the nanotubes of each point are separated and maintained inposition by means of a filler that is, for example, made of a pluralityof nonactive nanotubes.

Preferably, each pixel includes a multiple of three active nanotubesrespectively connected in parallel.

Preferably also, the end of each active nanotube of each pixel iscovered by a luminophore of one of the primary colours

BRIEF DESCRIPTION OF THE DRAWING

The invention will be better understood, and other aims, advantages andcharacteristics of it will appear more clearly from the followingdescription of the preferred embodiments given as non-limiting examplesand illustrated in the accompanying drawings, wherein:

FIG. 1 is a partial schematic representation seen from below of atouch-sensitive matrix screen according to the invention.

FIG. 2 is a sectional view of the cathode ray tube of FIG. 1 accordingto a first embodiment of the invention; and

FIG. 3 is a sectional view of the cathode ray tube of FIG. 1 accordingto a second embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

We will now refer to the annexed drawings, which are only illustrative,mainly because the scales are not respected. In fact, the diameter of ananotube is about twenty nanometres (20×10⁹ m), while the elementarypitch of a dot is about 0.2 millimetres (200×10⁶ m).

In FIG. 1, a corner of a cathode ray tube 10 according to the inventionis partially and schematically represented seen from above, that is tosay, as seen by the user. This cathode ray tube 10 includes a greatplurality of dots 12 substantially but no necessarily squared on oneside of about 200 μm.

Each dot 12 includes a pixel and an inputting element.

The pixel is made up of at least one set of three independent parallelnanotubes 14, 16. 18, each emitting in one of the primary colours usedin television or computer screens, namely red, green, and blue.

In order to increase the brightness of the resulting cathode ray tube,several nanotubes can be electrically connected in parallel in a samedot 12 and emitting in a same primary colour. In this case, each pixelof each dot 12 includes a multiple of three active nanotubesrespectively connected in parallel.

The inputting element is made up of a fourth nanotube 20 whose apparentend operates then as the electrode of a field effect transistor.

In a practical and advantageous way, the non-apparent ends of thenanotubes are directed in group into a collector 22 and connected to asocket 24 forming a connection for a central unit forming a controldevice and detection device (not represented in the figures).

The active nanotubes 14, 16, 18, 20 of each dot 12 are separated andmaintained in position by means of a filler 26. This filler 26 isadvantageously made up of a plurality of non-active nanotubes and/or ofother nanoparticles such as carbon.

According to a first embodiment disclosed in FIG. 2 representing thematrix cathode ray tube of FIG. 1 in a sectional view, wherein only twonanotubes 14 and 16 have been represented, these nanotubes 14,16 arebent in order to form a group of nanotubes whose other ends areconnected to the central unit.

A luminescent film 30 is placed on the dots 12 facing the user, mainlyto protect them, while a protection sheet 32 is applied on the oppositeside.

According to another embodiment disclosed in FIG. 3 which representsalso a schematic sectional view, the cathode ray tube of FIG. 1, thenanotubes 14, 16 14, 16′, etc., are arranged in parallel and are notbent. An electric conductor 34, 34′ etc. is connected to each nanotube14, 16 in order to apply the electric voltage required to thenon-visible end of the nanotubes. These conductors are reconducted tothe connector 24 by means of the collector 22.

A protection sheet 32 is glued to the surface of the conductors 34, 34′on the lower invisible side of the cathode ray tube 10.

The visible end of each of the active nanotubes 14, 16, etc. is coveredby a luminophore 36 emitting in one of the three primary colours asdescribed previously.

A transparent plastic film 30 covers the cathode ray tube. This film iselectrically insulated from the ends with reference to the nanotubes. Itis a conductive film connected to a reference potential, for example,the earth 38, in order to form an anode for the plurality of cathodesmade up of the pixel nanotubes.

Preferably, the nanotubes 14, 16, etc. are created directly on and in asheet woven in carbon fibres which is found under the reference 43 inFIG. 3, since this sheet then acts as support of the nanotubes.

It will be obvious to those skilled in the art that in this way weobtain a touch-sensitive matrix screen 10 having the above-mentionedadvantages. Such a cathode ray tube can easily be obtained in all thedesired sizes, for example for a roadsign or a hoarding, or for the dialof a watch, or a visualisation screen fixed to a plastic card of thesmart card type, eventually with photovoltaic cell allowing anautonomous electric feed.

This screen is not fragile, it is also flexible and can from there bewound on itself when transporting it. Furthermore, the little electricpower required for it to function allows using it in a rather hostileenvironment.

A particular advantage of such a touch-sensitive matrix screen is thatit is possible to use it as a table to put, for example, a map or apaper document on it, and to obtain very simply a computing input of themap simply by following the drawn lines by means of a stylus or even afinger.

Although we have represented and described what is presently consideredto be the preferred embodiments of the invention, it is evident thatthose skilled in the art can add different changes and modificationswithout exceeding the scope of this invention as defined by the annexedclaims.

It is clear that the utilisation of such a touch-sensitive matrix screendoes not prevent the data inputting by conventional means such as akeyboard, a mouse, or a joystick.

What is claimed is:
 1. Touch-sensitive matrix screen for inputting anddisplaying data comprising a plurality of carbon nanotubes defining aplurality of pixels and a plurality of inputting elements, wherein itconsists of a dot matrix of each dot comprising a pixel and an inputtingelement, each pixel made up of ends of at least three mutually parallelnanotubes and each transmitting in one of the three primary colours, theinput element being made up of the end of at least a fourth nanotube. 2.Matrix screen according to claim 1 wherein each dot consits of aplurality of nanotube ends of which at least four are made active. 3.Matrix screen according to claim 1, wherein the nanotubes of each dotare separated and maintained in position by means of a filler.
 4. Matrixscreen according to claim 2, wherein said filler is made up of aplurality of non-active nanotubes.
 5. Matrix screen according claim 1,wherein each pixel includes a multiple of three active nanotubesrespectively connected in parallel.
 6. Matrix screen according to claim1, wherein the end of each active nanotube of each pixel is covered by aluminophore of one of the primary colours.
 7. Matrix screen according toclaim 1, wherein said nanotubes are bent in such a way to form a groupof nanotubes, the other ends of which are connected to a central unitcomprising a control device of the nanotubes constituting the pixels anda detection device for nanotubes constituting the inputting elements. 8.Matrix screen according to claim 1, wherein said nanotubes arerectilinear and mutually parallel, the ends opposite to said dots beingconnected to a central unit comprising a control device of the nanotubesconstituting the pixels and a detection device for nanotubesconstituting the inputting elements.
 9. Matrix screen according to claim1, wherein the surface built by said dots is covered by a transparentplastic film.
 10. Matrix screen according to claim 9, wherein saidplastic film is a conductive film forming a plurality of anodes in frontof the corresponding plurality of ends forming cathode of the nanotubesconstituting the pixels and insulated from them.
 11. Matrix screenaccording to claim 9, wherein said plastic film is luminescent. 12.Matrix screen according to claim 1, wherein the nanotubes are created ona sheet woven in carbon fibres.
 13. Matrix screen according to claim 2,wherein the nanotubes of each dot are separated and maintained inposition by means of a filler.
 14. Matrix screen according to claim 10,wherein said plastic film is luminescent.